This invention relates to apparatus for boring of a new hole or reboring of an existing hole in a workpiece wherein the new hole or the hole to be rebored is spaced apart from a different hole or other location on the workpiece. That is, the workpiece may exist with two holes therein, one or both of which need to be rebored, or the workpiece may have a first hole and may need a second hole bored in the workpiece at a location which is to be precisely spaced-apart from the first hole. Commonly, the present invention is employed in combination with a portable boring bar.
U.S. Pat. No. 5,785,466 (the '466 patent) discloses a tool for aligning a portable boring bar for reboring one or more existing holes in a workpiece. As disclosed in the '466 patent, the need for the aligning tool is frequently found when repairing heavy earth-moving type machinery which employs articulating joints as a part of the machine. The '466 patent is incorporated herein in its entirety by reference.
As pointed out in the '466 patent, in many applications, the points of articulation include multiple bores. In substantially all instances, the articulating joint includes two structural items, one of which is articulated relative to the other item, and each structural item has its own set of bores. The bores of a first set are disposed in a first structural member of the machine and the second set of bores are disposed in a second structural member of the same machine. For articulation of the first and second structural members, the bores in one set must be in register with the bores of the second set and some form of pin or other removable connector passed through the registered bores to define the articulation joint. Thus, the axes of the bores of a first set must be parallel to one another, must be perpendicular to an outer surface of their structural member, and spaced apart by a precise distance. Likewise, the axes of the bores of the second set must be parallel to one another and perpendicular to an outer surface of their structural member, and spaced apart from one another by a precise distance, such distance being precisely equal to the distance separating the bores of the first set.
The present inventor has found that it is also of importance that, when reboring a bore it is most important that the axis of the resultant rebored bore not only be parallel to the axis of a second (or base) bore, but the distance between the axis of the base hole and the axis of the rebored bore be spaced apart by a very precise distance. Failure to form the bores of a first set of holes in a first structural item with their axes both parallel to one another and precisely spaced apart, and to form the holes of the second set of holes in a second structural item with their axes both parallel to one another and precisely spaced apart by the same distance at which the holes in the first set are spaced apart, results in failure of the rebored hole and the base hole of the first set of holes in the first structural item to line up (be in register) with matching holes in a second set of holes in the second structural item. This misalignment of the bores can result in malfunctioning of the articulation action of the joint.
By “precisely”, it is meant that the distance between any two holes of a set should be equal to the desired spacing ±0.01 inch or better. The significance of this degree of precision will be recognized when one notes that the structural items involved in the articulating joint of a piece of heavy duty earth moving machinery weighs hundreds of pounds and are relatively huge in bulk, hence they must be manipulated by a crane or other mechanical lifting and positioning device when being assembled. Accordingly, failure to provide precisely positioned and parallel holes (bores) in both of the structural elements may completely preclude the joining of the articulating structural elements, or may result in improper alignment of these elements and resulting undue wear of the holes due to their misalignment. Also, importantly, when assembling the heavy and huge structural items, a worker's manual attempts to move or rearrange the structural items to align their respective sets of holes can be frustrating, but more importantly, can result in serious injury to the worker.
Accordingly, there is a need in the industry for a tool which is capable to aligning first and second holes, with their respective axes being parallel to one another and precisely spaced apart from one another.